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Are old kites/bar systems obsolete?

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tegirinenashi
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Re: Are old kites/bar systems obsolete?

Postby tegirinenashi » Sat Aug 05, 2017 8:55 pm

NorCalNomad wrote:
Sat Aug 05, 2017 8:40 pm
modern kites are WAY better
They are not. The only convenience missing on Waroo is single inflation point system; but you know what? They are lighter and struts can be pumped to higher pressure (because lower diameter struts can hold higher psi). And what did North came up with this year? They upped the struts inflation rubber hoses from 6 mm to 9 mm? That is just pathetic.

The kitesurfing industry is clutching at straws. Genuine innovations such as inflatable kite, 4 line control bar, bow kites, hydrofoil, come once in a decade.

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Re: Are old kites/bar systems obsolete?

Postby NorCalNomad » Sun Aug 06, 2017 1:53 am

tegirinenashi wrote:
Sat Aug 05, 2017 8:55 pm
NorCalNomad wrote:
Sat Aug 05, 2017 8:40 pm
modern kites are WAY better
They are not. The only convenience missing on Waroo is single inflation point system; but you know what? They are lighter and struts can be pumped to higher pressure (because lower diameter struts can hold higher psi). And what did North came up with this year? They upped the struts inflation rubber hoses from 6 mm to 9 mm? That is just pathetic.

The kitesurfing industry is clutching at straws. Genuine innovations such as inflatable kite, 4 line control bar, bow kites, hydrofoil, come once in a decade.
I see you ride with old gear and feel the need to justify that.

I see you also have been misinformed. The ability for a container, eg bladder, to hold to a higher pressure has no relation to it's diameter.

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Re: Are old kites/bar systems obsolete?

Postby Matteo V » Sun Aug 06, 2017 2:24 am

NorCalNomad wrote:
Sun Aug 06, 2017 1:53 am

I see you also have been misinformed. The ability for a container, eg bladder, to hold to a higher pressure has no relation to it's diameter.
Just need to correct this - NorCalNomad is not completely wrong on this, but the statement is misleading.

The bladder is not the container resisting deformation. It is a liner capable of only holding a fraction of a PSI on it's own. This is the reason that leaks are best found while the bladder is still in the leading edge. The leading edge fabric is the container under strain from the pressure contained within the bladder. Or rather it stops the weak (but air tight) bladder from expanding like it would if inflated outside of the leading edge fabric.

Then, NorCalNomad incorrectly leads you to believe that pressure limit is not directly tied to diameter. It is ABSOLUTELY tied to diameter. It is one of the variables in the equation that determines allowable stress in the container walls. The larger the diameter of the container for a given pressure, the more stress on the container walls (trying to rip the container apart).

So with a smaller LE, you can pump to a higher pressure and not worry about the fabric or stitching ripping. However, in relation to stiffness, a kite of larger diameter requires a lower pressure to be as resistant to bending/buckling. So that is why you NEED to pump up smaller LE kite to a higher pressure than larger LE kites.

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tegirinenashi
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Re: Are old kites/bar systems obsolete?

Postby tegirinenashi » Sun Aug 06, 2017 3:13 am

Matteo V wrote:
Sun Aug 06, 2017 2:24 am
NorCalNomad wrote:
Sun Aug 06, 2017 1:53 am

I see you also have been misinformed. The ability for a container, eg bladder, to hold to a higher pressure has no relation to it's diameter.
Just need to correct this - NorCalNomad is not completely wrong on this, but the statement is misleading.
What do you mean by "misleading"? This is not political/social studies where there is no wrong answers. In hard sciences you are wrong or you are right. Completely.

To put it in the layman terms, and in the content of the prior one pump discussion, if one can safely pump the LE to 6 psi, and kite struts are twice as thin, they can be safely pumped to 12 psi (which is impossible to achieve with one pump system). As you pointed out, this is law of physics, so it has all kind of applications beyond kitesurfing. For example, thinner 22mm bicycle race tubes are advised to be pumped to 100 psi, while 28 mm road tires to only 50.

Now, let's again analyse the "latest and greatest" North innovation of increasing the hose diameter. It is moronic at least for two reasons:
1. Higher diameter means increased weight.
2. Higher diameter tubes can withstand less pressure, so you need to reinforce them by making thicker, increasing the weight even more!

Again, I have nothing against one specific company. This is just one more exhibit to add to the official thread of pointless innovations .
Last edited by tegirinenashi on Sun Aug 06, 2017 3:37 am, edited 2 times in total.

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Re: Are old kites/bar systems obsolete?

Postby Matteo V » Sun Aug 06, 2017 3:33 am

tegirinenashi wrote:
Sun Aug 06, 2017 3:13 am

What do you mean by "misleading"? This is not political/social studies where there is no wrong answers. In hard sciences you are wrong or you are right. Completely.
I was referring to how NorCalNomad is referring to the "bladder" as the containment vessel. I cannot call the science wrong as he is not even in the ball park to do the science. In order to get to the math, we would need to be talking about the same part.

Also, you are correct in your veiled accusation that I am trying to be somewhat PC on this criticism. I find it much easier to convince someone that they are wrong if I withhold personal attacks. The benefit is that you can often convince someone to accept the correction and admit fault with their argument. This allows bystanders, who may never do the math themselves, the ability to see that the opposition has reversed their position based on evidence. This tends to reduce beliefs in incorrect concepts much better than just calling some one an a--hole. Simple fact is that some people shut down conversation when called out in a disrespectful manner.

Funny how in another thread tonight, there was no other option but to call a poster out on their BS. But I still offered friendly advice as to how things work. I hope I have clarified and given you some friendly advice also.
Last edited by Matteo V on Sun Aug 06, 2017 4:14 am, edited 1 time in total.

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Re: Are old kites/bar systems obsolete?

Postby NorCalNomad » Sun Aug 06, 2017 3:41 am

If you want to ride on old gear that sucks...go ahead. But a Best Waroo, Cabrihna co2 and Naish x2 all are bad kites by today's standards.

Yes, I was over simplifying the maths on the pressure bit, but conjecturing that older LE's that had to be pumped up harder (which put more strain on the materials) is misinforming people.

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Re: Are old kites/bar systems obsolete?

Postby Tone » Sun Aug 06, 2017 4:03 am

Old kit is not great, it will work but won't be great.

That's all.

Newer kit has better safety etc...

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Re: Are old kites/bar systems obsolete?

Postby Matteo V » Sun Aug 06, 2017 4:09 am

NorCalNomad wrote:
Sun Aug 06, 2017 1:53 am
The ability for a container, eg bladder, to hold to a higher pressure has no relation to it's diameter.
No shame in admitting it. I have admitted fault with my predisposition that leashes were a stupid idea in EVERY case. Others presented evidence to convinced me and I no longer espouse my initial incorrect position to those I see wearing leashes.

So I have to say that when you state "I was over simplifying the maths on the pressure bit", well....... we are still in the same boat with some onlookers in the forum possibly believing that your original quote is not categorically wrong.

Again, I have admitted that my views were wrong in the past. You seem to be half way there. Let's correct this by admitting that "no relation" in the highlighted quote needs to be changed to "is directly related".

And sincerely thank you for your contribution to the forum. By being wrong on my leash position, I still furthered discussion and clarified the issue for all. By being wrong on the pressure issue, you have helped many who may have had the same misconceptions.

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Re: Are old kites/bar systems obsolete?

Postby Flyboy » Sun Aug 06, 2017 5:31 am

The pressure/bladder/diameter question is a bit of a distraction. In principle, kite manufacturers would like you to believe that the next year's kites are an impressive improvement on the previous year's. They do this to encourage people to spend money buying new kites which makes their businesses more profitable. Marketing 101. Anyone who has spent time reading through some of the threads on this forum would be aware that frequently the "improvements" made turn out to be failures - or at least partial failures.

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Re: Are old kites/bar systems obsolete?

Postby Matteo V » Sun Aug 06, 2017 5:19 pm

Flyboy wrote:
Sun Aug 06, 2017 5:31 am
The pressure/bladder/diameter question is a bit of a distraction. In principle, kite manufacturers would like you to believe that the next year's kites are an impressive improvement on the previous year's. They do this to encourage people to spend money buying new kites which makes their businesses more profitable. Marketing 101. Anyone who has spent time reading through some of the threads on this forum would be aware that frequently the "improvements" made turn out to be failures - or at least partial failures.
That is a good over view of how it works and I cannot find any fault with your statement. But a detailed examination of this overview can lead to some interesting areas. That is the great thing about posts taking a detour from the original question or statement.

Take, for example, the problem of "Scaling issues" - one size LE across the entire size range of a particular kite can create a different feel in your small kites compared to your medium sized kites. This was known for years and that is why larger sized kites had larger sized leading edges. Have the designers found a way to cope with this issue? Or have they reintroducing an old problem that was adequately solved, only to be revisited again. Interesting topic and I would love to hear from a designer on this.


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